HMS Astute, a nuclear-powered attack submarine, sails up the Clyde towards the Faslane naval base in Scotland © PA

Britain’s nuclear force suddenly finds itself high on the political agenda. The government is intent on replacing the fleet of ageing Vanguard-class submarines that carry Trident missiles, a decision expected to be put before parliament next year. Yet many doubts still surround the project. Last weekend Scottish Labour joined the Scottish National party in opposing renewal of the deterrent based at Faslane, west of Glasgow; south of the border, meanwhile, the resistance of many Labour MPs to an anti-nuclear policy that damaged the party electorally in the 1980s will soon be tested by the stance of the party’s new leader, Jeremy Corbyn. Even some defence specialists who are not against Trident in principle question whether it adds much deterrent value, given that the UK is allied to a nuclear superpower. Others worry about the Americans no longer taking their obligations to defend their European allies seriously at a time when Russia is ever more prepared to make nuclear threats, as has been evident during the crisis over Ukraine.

While this debate rages, spare a thought for those on board the four Vanguard submarines, one of which is on patrol at any time, ready to launch its nuclear-tipped Trident missiles if ordered to do so. Were this to happen the crew would have failed in their core mission, which is to deter attack on the UK, yet they must nonetheless train as if the order could come at any time. Continuous patrol requires keeping these complicated boats, powered by their own nuclear reactors, safe and effective underwater for months at a time.

The particular physical and psychological demands faced by submariners as they operate in the “silent deep” inform this full and vivid account of the history of the submarine service since 1945 by Peter Hennessy and James Jinks. It is about much more than the nuclear force. Submarines are versatile military instruments, suitable for intelligence-gathering as well as sinking enemy ships and for launching strikes against targets on land. They made the difference in the 1982 Falklands campaign: after HMS Conqueror sank the General Belgrano, the Argentine Navy did not venture out to sea again.

This is a perfect topic for Hennessy, a historian who has long been fascinated with the workings of the British state, especially in its most secret pursuits. With Jinks, whose PhD he supervised, as co-author and with considerable help from the Royal Navy, the result is an account remarkable for its range and detail, well illustrated and with excellent maps. It covers higher policymaking on the nuclear force; stories from the cold war, when British and Soviet submarines spent much time trying to get on each other’s tails; reconstructions of operations in the waters around the Falklands; reports of accidents; and technical explanations of changing design and construction techniques.

Prime ministers are quizzed on their feelings about writing the “letter of last resort”, instructing commanding officers what to do if nothing were left of their country. The authors can barely suppress their excitement as they accompany those being trained to drive submarines and watch the test launch of a missile. Through all of this they give the submariners a voice, admire their professionalism and commend their contribution to national security.

A key theme is the American connection. Submarines and missiles were two areas in which it became painfully apparent during the 1950s that Britain would fall well behind unless it could draw on US technology. Hennessy and Jinks describe Lord Louis Mount­batten’s efforts as First Sea Lord to win over a man he described as a “stormy petrel”, Admiral Hyman Rickover — the formidable figure responsible for getting American submarines nuclear-powered. As supplicants, the British had no choice but to cope with Rickover’s legendary rudeness.

More cordial personal relations were in play at the end of 1962, when Harold Macmillan persuaded President John F Kennedy to agree to the British purchase of submarine-launched Polaris missiles. This was after the Pentagon had decided to cancel the Skybolt missile upon which the Royal Air Force had been relying. In this way, responsibility for nuclear deterrence was taken away from the RAF, which saw this as its core mission, and given to the Royal Navy, which regarded it as an expensive distraction from the business of maintaining a surface fleet. The then-First Sea Lord, Caspar John, a naval aviator, wrote in his diary of the “millstone of Polaris hung round our necks . . . potential wreckers of the real Navy”.

Dependence on American technology and facilities means that Washington could make it difficult for Britain to maintain a nuclear force, but it could neither do so quickly nor interfere with command procedures in the middle of a crisis. Kennedy had wanted to curtail Britain’s operational independence. Under pressure, Macmillan agreed to commit the Polaris force to Nato but then inserted the crucial exception, reserving the right to use it independently when “supreme national interests are at stake”.

Did the Falklands constitute one of those moments of supreme national interest? After the war, stories circulated that the use of Polaris had been considered. As official historian of the Falklands campaign, I explored this fully and found no evidence at all. Hennessy and Jinks recognise that, yet maintain the doubt by citing a conversation with the late Michael Quinlan, the civil servant who did most to fashion British nuclear policy. He recalled a “terrifying” suggestion from Margaret Thatcher that “she would have been prepared actually to consider nuclear weapons had the Falklands gone sour on her”. I had the same conversation with Quinlan. He was not in the Ministry of Defence at the time of the Falklands and these remarks came well after the event. It was perfectly in character for Mrs Thatcher to play to her “Iron Lady” image in this way. In practice, there were no scenarios where using Polaris could have been seriously considered. Only slightly more plausible might have been the use of nuclear depth charges, but the prime minister was as alarmed as her war cabinet colleagues when she discovered that these weapons were en route to the south Atlantic on surface ships as a matter of naval routine.

Hennessy and Jinks discuss with submariners how they feel about being able to inflict nuclear destruction. Rationalisations, they suggest, tend to refer to the credibility of a deterrence posture and the unlikelihood that they will be put to the ultimate test. Perhaps a more immediate concern is the possibility of a major incident while on patrol. Part of the admiration felt for submariners lies not only in the enclosed conditions in which they must live but the thought of what it would be like to be caught without escape in the event of mechanical failure or accident. Staying out of sight has political consequences as well as operational benefits, for it means that the complex and demanding nature of submarine work has been poorly understood. Hennessy and Jinks have ensured that this need no longer be the case.

Sir Lawrence Freedman is emeritus professor of war studies, King’s College London, and author of ‘Strategy: A History’ (OUP)

The Silent Deep: The Royal Navy Submarine Service since 1945, by Peter Hennessy and James Jinks, Allen Lane, RRP£30, 864 pages

Photograph: PA

Letter in response to this review

Trident debate assumes it is still relevant today / From John Fraser

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